The officers were attempting to establish whether nursery workers received the minimum wage.

The judge said that Aguda had “demonstrated a clear and deliberate intent to obstruct officers and this was a scandalous breach of the legislation”.

Andy Millican, criminal investigation team leader at HMRC, said: “This prosecution sends a clear message to employers that HMRC will actively pursue those we suspect of flouting the national minimum wage law. If employers obstruct us and refuse to comply with the law, they could receive a fine and a criminal record.”

The are six potential offences under section 31 of the National Minimum Wage Act. Each carries a maximum £5,000 fine and a criminal record.

TUC general secretary Brendan Barber said: “It is good to see Revenue and Customs take this tough line. It is simply not good enough merely to make employers pay employees what they should have been paid. They should be punished as well.”

The adult minimum wage rate is £5.35 an hour, increasing to £5.52 in October.